It is proposed to continue studies on the bacterial glycogen biosynthetic enzymes. Emphasis will be on the regulatory and catalytic properties of the ADPglucose pyrophosphorylase from E. coli B and from various photosynthetic bacteria. Chemical modification studies will be used to characterize and define the allosteric effector and catalytic sites of the enzyme. Comparative studies at the protein sequence level will be made in order to relate structure with function and specificity at these various ligand binding sites. Furthermore a study of kinetically altered ADPglucose pyrophosphorylases from E. coli glycogen mutants is initiated to determine the relationship of allosteric function with the primary structure of the ADPglucose pyrophosphorylase. The characterization of E. coli B glycogen synthase and branching enzyme with respect to reaction mechanism and the various amino acids involved in catalysis will be continued. Studies on the cloning of the glycogen biosynthetic structural genes of E. coli K12 will be continued so that future studies on DNA sequence analysis of the glg structural genes and on the genetic regulation of the biosynthesis of the glycogen biosynthetic enzymes can be initiated.